Hot water boiler



FIG. 1 is a perspective view of a hot water boiler showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken lines depict portions of the hat water boiler which form no part of the claimed design.

The dot-dash broken lines depict a boundary which forms no part of the claimed design. 

CLAIM The ornamental design for a hot water boiler, as shown and described. 